Homopolar Motor | Simple Electric Motor

This is probably among the candidates for the World's simplest electric motor. A 1.5 volt cell, a steel screw, a rare earth magnet and a piece of electric wire.

The screw/magnet assembly is suspended under the battery due to magnetic attraction. Using the wire, the battery is essentially short-circuited via the magnet and the screw.

This leads to a high electric current flowing through the magnet, and the current's resulting magnetic field is perpendicular to that of the magnet, causing the magnet to rotate.

Needless to say, it is a very inefficient electric motor design.